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Serial Lines Explained
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dc(4) Kernel Interfaces Manual dc(4) Name dc - serial line/mouse/keyboard Syntax device dc0 at ibus? vector dcintr Description The serial line controller provides four ports, with modem control on two of the ports. The DECstation 3100 and DECstation 2100 only pro- vide partial modem control. The DECstation 5000 provides full modem control. The ports are used as follows: Port Usage 0 Graphics device keyboard at 4800 BPS 1 Mouse or tablet at 4800 BPS 2 Communications port 1 (w/modem control)/local terminal 3 Communications port 2 (w/modem control)/local terminal Each communication port from the serial line controller behaves as described in and can be set to run at any of 16 speeds. For the encod- ing, see When a graphics device is not being used as the system console, communications port 2 becomes the system console. In this configuration, the port can only be used at 9600 BPS and no modem control is supported. The serial line driver operates in interrupt-per-character mode (all pending characters are flushed from the silo on each interrupt). Restrictions Speed must be set to 9600 BPS on the console port and 4800 BPS on ports used by graphics devices. The serial line driver enforces this restriction; that is, changing speeds with the command may not always work on these ports. Files console terminal local terminal local terminal See Also console(4), devio(4), tty(4), ttys(5), MAKEDEV(8) RISC dc(4)
